When one's glutenous maximus/minimus and scrotum/vagina bask in heat, sweat, love juices and leftovers from wiping unsuccessfully collect on one's gooch/taint/perineum. One must then take their index finger, wipe it along the taint to gather all the excrement, and transfer the nightmare fuel to the upper lip/Cupid's bow of a friend, foe, family member, or random human being to portray a Hitler mustache.

Siah: I'll Dutch Oven you!
Caly: Oh yeah? I'll give you one hell of a vinegar hitler!
Siah: What's that?
Caly: It's when I wipe my gooch sweat under your nose.
Siah: I'll drown you in a bucket of bleach if you ever do that to me.